It's likely worth noting that even crazy of all crazies, Crazy Jim chopped his booster in the most famous of all build threads.
Link please!
It's likely worth noting that even crazy of all crazies, Crazy Jim chopped his booster in the most famous of all build threads.
It's likely worth noting that even crazy of all crazies, Crazy Jim chopped his booster in the most famous of all build threads.
I cried reading that build thread so sad
but would he add these days with Loki case out since then ?
I cried reading that build thread so sad
but would he add these days with Loki case out since then ? or wuss out ?
https://www.csrocketry.com/rocket-m...oki-research-m1378-loki-red-rocket-motor.html
You just need a thin spacer. I used masking tape and built it up until it was high enough, maybe a dozen wraps. The width was only about an eighth of an inch.I may chop mine too. First I need to sort out fixing the tailcone for Loki motors when I installed it for aerotech. Silly me.
You just need a thin spacer. I used masking tape and built it up until it was high enough, maybe a dozen wraps. The width was only about an eighth of an inch.
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I built it with an aerotech. When I put in Loki or Gorilla cases I have a gap between the cone and the BT. Only solution I see so far is a tiny BT spacer, or to yank the aeropack, trim the MMT then reinstall.
Didn't it come with a spacer? Every tail cone I bought, spacer was included.
I built it with an aerotech. When I put in Loki or Gorilla cases I have a gap between the cone and the BT. Only solution I see so far is a tiny BT spacer, or to yank the aeropack, trim the MMT then reinstall.
Didn't it come with a spacer? Every tail cone I bought, spacer was included.
The spacer that it comes with does not fit well with the Loki hardware, I can't recall if it is too big or small just that it was not a good fit.
That's odd. Loki is about all I use these days and have 4 rockets with tailcone and have no issues with fit.
Wasn't there a change in Loki hardware at some point where Scott moved the external thrust ring to a location that would match the dimension of the AT/ CTI thrust ring. I seem to remember something like that, but my memory could be faulty in this regard.
I built a 3" Darkstar for my L2. I've flown it 3 times and all four times it's shown the same behaviour. It has a very pronounced 'wiggle' for the first 1000ft or so of flight and then it straightens out and flies perfectly. I've flown it on an Aerotech I500T, Aerotech J450DM, and a Loki K527. It's 10.1 pounds without a motor. The slowest it sims off the rail is on the J450DM at 45.5 ft/s, the I500 and K527 both sim at 58 ft/s. The wind varied on the flights, but it was not what I would consider excessive on any of them.
Here is a screenshot of OR. Stability is 6.15 cal with the I500 in it. Stability is 4.41 cal with the K527.
View attachment 327022
When I launched it at NYPower in May, I talked with another guy who had built a 3" Darkstar. He told me that he'd had the same wiggle on his and cured it by chopping about a foot off the overall length of the rocket and putting a lighter nosecone on it.
I ran simulations in OR to compare stability on the rocket flying on the J450 at it's normal 88" length and again with 12" removed. It shows the rocket is less stable with the 12" removed. Here are the two graphs :
Full
View attachment 327023
Cut
View attachment 327024
I'll attach the OR file as well.
Can someone help me understand why this is happening and if chopping 12" off the rocket will help or hinder this problem?
cheers - mark
Ditto. Mine flies straight as an arrow every time. I did my L2 on a CTI J400, as it was smooth as silk.Curious - how long is the rail you are using? On a Loki K527, mine is about 71 fps off the rail. Many flights and always straight as an arrow.
Ditto. Mine flies straight as an arrow every time. I did my L2 on a CTI J400, as it was smooth as silk.
I'd be curious as to ground equipment. How steady are the launch pads? Sitting on firm ground? Otherwise, I don't know. Mine is fine. Good luck in solving the problem!
I disagreeground equipment isn't going to cause this.
I disagree
Ah, I see.We're discussing this behavior- https://www.rocketreviews.com/coning.html
I don't understand all the reasons for it, or when and why it happens. But it's an in flight thing that happens with overstable rockets, and not all the time.
Ah, I see.
I disagree that the issue at hand is actually coning.
Ah. That's possible. I was referring to the original post that said it straightened out after 1000 feet. Definitely a different story at 5ka fair stance. However, I've seen my photos, and others videos, and it certainly seems like it is. I'll dig out my photos and see if it shows it well, but it's a spiral smoke trail at 5-7,000 feet that's too smooth to be the smoke drifting
Ah. That's possible. I was referring to the original post that said it straightened out after 1000 feet. Definitely a different story at 5k
Apologies to the OP for the thread hijack, however after thinking about the different Loki experiences with the Aeropack Tailcone, I figured there has to be something to it.
So I checked out my Loki hardware. Fortunately I have the full Loki 54mm set including two 54-2800 cases. One is older and one is newer with a lighter blue anodizing.
If I remove the external snap-ring from one of the cases and line it up with the other, by inserting the outside edge of the snap-ring into the other cases snap-ring groove, there is a visible difference.
That difference is roughly .05 closer to the aft end on the new case as compared to the old case.
Also overall the new case overall length is shorter. I did not measure it but with the snap-ring grooves still lined up you can see that the lighter anodized case is also shorter on the forward end.
The difference between where the snap-ring groove lines up does not sound like much, but when I use the newer case in my Darkstar, with the Aeropack spacer on the forward side of the snap ring, it fits perfectly almost.
Using the spacer on the aft side of the snap-ring using the new and old case results in roughly 3/16ish recess which is sloppy play.
With the spacer on the forward side of the snap ring on my older set of hardware it results in the issue I mentioned in a previous post where the retainer does not fully seat.
With the newer hardware the retainer fully seats with the spacer on the forward side of the snap-ring and with a very marginal amount of play, certainly not enough to be a concern in my opinion.
So Tims AKA timbucktwo, experience is completely valid, as is mine. It needs to be qualified based on the hardware. Now the next question I would have is are the differences based on generational differences in hardware, or tolerances in the manufacturing process.
As I mentioned earlier, Scott made the change so his newer motors would fit Aeropack. I believe this happened after he purchased Loki.
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